Converging sources of research indicate that the right cerebral hemisphere may age sooner than the left, as evidenced by a performance decrement on tasks assessing functions specialized to the right hemisphere. Such a decrement is not seen for tasks assessing functions specialized to the left hemisphere. Recently, however, mixed results have been obtained in studies which address this issue directly by employing methods based in cognitive psychology and hemispheric laterality. The scientific purpose of this proposal is to investigate right hemiaging with divided attention/dual task methods. It has been proposed that each cerebral hemisphere might be viewed as having an independent pool of capacity. When two tasks drawing on a single pool are combined and demand exceeds capacity, a performance decrement results on one or both tasks. In order to test whether older individuals have a greater functional decrement in the right hemisphere than in the left, an experiment is proposed where single and dual tasks will be performed by both younger and older subjects, consisting of right and left index finger tapping, syllable repetition, and WAIS block design solution with the non-tapping hand. Previous research has indicated that for younger subjects these tasks demonstrate performance decrements when right finger tapping and block dsign solving are combined (both left hemisphere tasks), and when left finger tapping and block design solving are combined (both right hemisphere tasks). A significantly disproportionate interference effect for older subjects on the latter task will indicate greater right hemisphere functional decline. Practical gains to this research include the delineation of functional integrity and/or decrement in the two cerebral hemispheres in later life. Such a decrement will have important implications for the daily functioning of older adults. If, as previously suggested, the right hemisphere does show an age-related decline, manipulospatial activities may be negatively affected. The present study thus provides information relevant to issues of competence and well-being in later life.